Saturday, October 16, 2010

We know that casting a ballot in the voting booth involves politics, values and personalities. But before you ever push the button for your candidate, your brain has already carried out an election of its own to make that action possible. New research from Vanderbilt University reveals that our brain accumulates evidence when faced with a choice and triggers an action once that evidence reaches a tipping point.

The research was published in the October issue of Psychological Review.

"Psychological models of decision-making explain that humans gradually accumulate evidence for a particular choice over time, and execute that choice when evidence reaches a critical level. However, until recently there was little understanding of how this might actually be implemented in the brain,” a doctoral student in the Department of Psychology and lead author of the new study, says. "We found that certain seem to represent the accumulation of evidence to a threshold and others represent the evidence itself, and that these two types of neurons interact to drive decision-making.”

The researchers presented monkeys with a simple visual task of finding a target on a screen that also included distracting items. The researchers found that neurons processing visual information from the screen fed that information to the neurons responsible for movement. These movement neurons served as gatekeepers, suppressing action until the information they received from the visual neurons was sufficiently clear. When that occurred, the movement neurons then proceeded to trigger the chosen movement.